Reduction of n2o in the exhaust gas of lean-burn petrol engines

Patent metadata

Field	Value
Publication number	US-2016222901-A1
Application number	US-201414917860-A
Country	US
Kind code	A1
Filing date	Aug 20, 2014
Priority date	Sep 11, 2013
Publication date	Aug 4, 2016
Grant date	—

Abstract

The present invention relates to the use of different regeneration strategies for nitrogen oxide storage catalysts (NOx storage catalyst, LNT or NSC), depending on the exhaust gas temperatures, to reduce in the total exhaust gas the greenhouse gas N 2 O (nitrous oxide) that is produced as a secondary emission during the regeneration of the storage catalyst. If the exhaust gas temperature is below 275° C.-290° C., regeneration takes place using a strategy with short pulses of around 2 seconds and λ Lambda 0.95 rich.

First claim

1 . A method of reducing N 2 O formation during regeneration, comprising utilizing different strategies for the regeneration of one or more nitrogen oxide storage catalysts to reduce the N 2 O formation during regeneration, wherein the nitrogen oxide storage catalyst is used in the exhaust gas system of a spray-guided stratified operating petrol engine, wherein the different strategies are specifically selected based on the temperature of the exhaust gas such that below a temperature range of 275° C.-290° C. regeneration occurs with a shorter, but richer pulse of reducing agents than it does at temperatures above this temperature range.

2 . The method according to claim 1 , wherein, with regeneration strategies above this temperature range, a modulation of the λ-amplitude of the regeneration pulse is provided in such a way that a rich pulse is followed by a phase with an exhaust gas mixture at λ=1 (rich/λ=1 regeneration strategy).

3 . The method according to claim 1 , wherein shortest possible regeneration times of under 10 sec. are established.

4 . The method according to claims 1 , wherein regeneration is not carried out below λ=0.87.

5 . The method according to claims 1 , wherein the exhaust gas composition is set by injecting fuel into the cylinder of the engine or by an injection mechanism into the exhaust gas system upstream of the nitrogen oxide storage catalyst.

6 . The method according to claims 1 , wherein the regeneration of the nitrogen oxide storage catalysts is controlled by sensors or based on modeling.

7 . The method according to claims 1 , wherein the nitrogen oxide storage catalysts are contained in an exhaust gas cleaning system having one or more three-way catalytic converters arranged in proximity to the engine and one or more nitrogen oxide storage catalysts arranged in proximity to the engine.

Assignees

• Umicore Ag & Co Kg

Inventors

• Adam Frank
• Eckhoff Stephan
• Mueller Sebastian

Classifications

• F01N3/0814 Primary

  combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts · CPC title

• F01N3/0871

  using means for controlling, e.g. purging, the absorbents or adsorbents · CPC title

• F02D41/1446 Primary

  the characteristics being exhaust temperatures · CPC title

• F01N3/0842

  Nitrogen oxides · CPC title

• F01N3/101

  Three-way catalysts · CPC title